Pathology Of Human Eye

Question 1

Blepharitis

Answer 1

• Inflammation of the eyelids
• Usually involves part of eyelid where eyelashes grow and affects both eyes
• commonly occurs when tiny oil glands located near base of eyelashes become clogged (leads to irritation and red eyes)
• chronic, hard to treat, but no permanent eyesight damage and not contagious

Question 2

Chalazion

Answer 2

• cyst in the eyelid due to blocked oil gland
• the blocked gland is usually the meibomian gland but can also be the gland of Zeis
• occur in middle of eyelid, red and is a painless granuloma of meibomian gland
• they tend to come on gradually over a few weeks

Question 3

Hordeolum

Answer 3

• localized infection or inflammation of the eyelid margin involving hair follicle leads of the eyelashes or meibomian glands
• usually painful, erythematous, and localized
• may produce edema of the entire lid
• purulent material exudes from the eyelash line in external hordeola while internal hordeola suppurate on the conjunctival surface of the eyelid

(This is painful, a chalazion is not)

Question 4

Dacryocystitis

Answer 4

• inflammation or infection of the lacrimal sac that occurs when the lacrimal drainage system is obstructed and bacteria infect the sac
• lacrimal sac is part of the system that connects the eye to the nasal cavity in order to drain tears away from the surface
• causes unilateral tearing, discharge, swelling, redness and pain in the inner inferior canthus
• may be acute or chronic and can be congenital or occur later in life
• chief sx: water eye, pain, redness and swelling in inner part of affected eyelid

Question 5

Periorbital Cellulitis

Answer 5

-infection of eyelid or skin around the eye
-commonly affects children under 18 months old, though can occur at any age
-can occur after a scratch, injury or bug bite around eye that allow germs to enter the wound
-can also extend from a nearby site that is infected such as the sinuses
Sx: redness around the eye or in the white part of the eye, swelling of the eyelid, whites of eyes, and surrounding area
-doesn’t affect vision or cause eye pain

Question 6

Conjunctiva

Answer 6

• translucent but contains prominent blood vessels and lymphatic channels
• strongly adherent at THE corneoscleral limbus and to the undersurface of lid; weakly attached elsewhere

Question 7

Conjunctivitis

Answer 7

• inflammation or swelling of the conjunctiva
• (transparent layer of tissue that lines the inner surface of the eyelid and covers the sclera of the eye)
• often called “pink eye”, it’s a common eye disease esp. in kids. It may affect one or both eyes. Some are highly contagious and can easily spread. While it’s usually minor, sometimes it can become serious
• viral or bacterial infection can cause this. It can also be an allergic reaction and STDS

Sx: gritty feeling in one or both eyes, excessive tearing, discharge from one or both eyes, swollen eyelids, pink discoloration to the whites of one or both eyes, increased sensitivity to light

Question 8

Allergic Conjunctivitis

Answer 8

• causes red, watery, itchy or gritty eyes
• not usually painful and doesn’t make eyes sensitive to light
• doesn’t affect vision
• most common to pollen in the hay fever season
• other allergies to house dust, mite, cosmetics, and problems with contact lenses
• eye drops ease symptoms

Question 9

Viral Conjunctivitis

Answer 9

• most commonly caused by contagious viruses associated with the common cold
• It can develop through exposure to coughing or sneezing of someone with a URTI
• can also occur as the virus spreads along the body’s own mucous membranes which connect lungs, throat, nose, tear ducts and conjunctiva
• since tears drain into nasal passageway, forceful nose blowing can cause a virus to move from respiratory system to the eyes

Question 10

Bacterial Conjunctivitis

Answer 10

• most commonly caused by staph or strep from skin or respiratory system
• insects, physical contact with other people, poor hygiene, or using contaminated eye makeup and facial lotions can also cause the infection
• sharing makeup and wearing contacts that aren’t your own or improperly cleaned can also cause this

Question 11

Uvea

Answer 11

-layer of tissue beneath the white of the eye (sclera)

3 parts: iris, choroid (layer of blood vessels and C.T. Between sclera and retina), and the ciliary body

Question 12

Uveitis

Answer 12

• inflammation of the uvea (middle layer of the eye that contains iris, choroid and ciliary body)
• can have many causes: eye injury and inflammation.
• exposure to toxic chemicals such as pesticides and acids used in manufacturing processes also can cause uveitis

Question 13

Anterior Uveitis

Most common-affects men and women equally

Answer 13

Inflammation of the iris or the iris and ciliary body

Sx: light sensitivity
Decreased visual acuity
Eye pain
Redness

Question 14

Intermediate Uveitis

Answer 14

Inflammation of the ciliary body

Usually painless
Sx: blurred vision and floaters (usually in both eyes)

Question 15

Posterior Uveitis

Answer 15

Inflammation of the choroid

Usually painless
Sx: blurred vision and floaters (usually in both eyes)

Question 16

Diffuse Uveitis

Answer 16

Inflammation of all areas of uvea

Question 17

Cornea

Answer 17

Transparent watch glass shaped structure that covers other anterior segment structures and forms anterior wall of anterior chamber

Question 18

Keratitis

Answer 18

• cornea becomes swollen and inflamed
• makes eye red and painful and affecting vision
• also known corneal ulcer
• some forms involve infection, including bacterial, viral, fungal
• contact lens wearers need to remember that infectious keratitis can result from not caring for contact lenses properly
• non-infectious form: simple fingernail scratch or from wearing contacts too long

Question 19

Optic nerve

Answer 19

Collected retinal nerve fibers from the entire retina exiting the globe posteriorly through cribiform plate of the sclera

Question 20

Optic Neuritis

Answer 20

• inflammation of the optic nerve
• sx: usually unilateral with eye pain and partial or complete loss of vision
• dx: primarily clinical.
• tx: directed at the underlying condition; most cases resolve spontaneously

-most common among adults 20-40. Most cases result from demyelination disease, particularly MS, in which there may be reoccurrences. Optic neuritis is often presenting manifestation of MS

Other causes: infectious (viral encephalitis, sinusitis, meningitis, TB, syphilis, HIV)

• Tumor metastasis to the optic nerve
• chemicals and drugs

Question 21

Crystalline Lens

Answer 21

• biconvex refractive structure
• located just behind plane of iris
• suspended by multiple zonular filaments

Question 22

Cataracts

Answer 22

• clouding of the lens in the eye which leads to dec. vision
• often develop slowly and can affect one or both eyes
• sx: faded colors, blurry vision, halos around light, trouble with bright lights and trouble seeing at night
• cause of half of blindness and 33% of visual impairment worldwide
• most commonly due to aging but may also occur due to trauma or radiation exposure, be present from birth or occur following eye surgery or other problems
• risk factors: diabetes, smoking tobacco, prolonged exposure to sunlight and alcohol
• either clumps of protein or yellow-brown pigment may be deposited in the lens reducing transmission of light to the retina at the back of the eye

Question 23

Diabetic Retinopathy

Answer 23

• diabetes complication that affects eyes
• caused by damage to the blood vessels of the retina
• at first, may cause no symptoms or just mild vision problems but can eventually cause blindness
• the condition can develop in anyone who has type I or II diabetes. The longer the diabetes and the less controlled the blood sugar, the more likely the development of diabetic retinopathy

Question 24

Stages of Diabetic Retinopathy

Answer 24

A: ischemic (nonproliferative): which involves small vessel occlusion, ischemia and pericyte degeneration (microaneurysms and anteriovenous shunts) and angiogenesis factor release. Cause of blindness: capillary leakage, macular edema and hemorrhages

B: proliferation: neovascular proliferation or protein leakage. Cause of blindness: vitreous hemorrhage

C: fibrotic: vitreous fibrosis, attachment to retina and contraction. Traction-induced retinal detachment

Question 25

Age Related Macular Degeneration

Answer 25

Initial Stage: drusen

Optic disc Drusen

Question 26

Melanoma

Answer 26

• choroid layer is the most likely site of melanoma in the eye
• the cancer may only be one the eye
• or it may spread and metastasize to another location in the body, most commonly the liver
• can also begin in the skin or other organs and spread to the eye
• melanoma is the most common type of eye tumor in adults. Even so, melanoma that starts in the eye is rare. Too much exposure to sunlight is an important risk factor
• people who have fair-skin and blue eyes are most affected

Sx: 
-bulging eyes
-change in iris color
-poor vision in one eye
-red, painful eye
-small defect on the iris or conjunctiva 
(Sometimes no symptoms)

Question 27

Retinoblastoma

Answer 27

• a malignant tumor of the retina
• may occur at any age but it’s most often in kids before age of 5
• affects on one every 18k births, with an estimated 250-500 cases diagnosed in US each year
• may be in one eye or both
• is usually confined to the eye but if left untreated is capable of metastasis or spreading to other parts of body

Sx:
Leukocoria (cat’s eye reflex or white pupil)
Misaligned eyes
Blurred vision
Alterations in RB1 or MYCN can give rise to retinoblastoma